An area of tire technology which has engaged investigators over the years is the run-flat pneumatic tire concept. A run-flat pneumatic tire is one designed to support a vehicle for operation even if the tire has partially or totally lost its inflation pressure. The advantages of such a tire in safety, convenience, cost and weight and space saving are obvious. A recent successful development in the art of run-flat tires is the band-reinforced radial tire designed by the inventor of the present application, which banded tire is the subject of U.S. Pat. No. 4,111,249, granted to Edward G. Markow and assigned to the assignee of the present invention. The run-flat tire in the Markow patent is hereby incorporated herein by reference.
A banded run-flat tire is a pneumatic radial tire having a casing with a crown and sidewalls extending from the crown on either side to annular beads, which, in conventional way, are used to mount the tire in a sealed relationship on the rim of a wheel. In the design the band element, which usually is a thin structural ring of high-strength steel or a fiber/epoxy composite, is incorporated circumferentially into the crown of the tire under the tread thereof. Radial tires, as is well known, have one or more plies containing a multiplicity of closely spaced radial reinforcing cords or wires in the sidewalls of the tire casing. In the tire disclosed in the above-referenced patent to Markow, the radial cords or wires function as spoke-like reinforcing elements to stabilize the circumferential band. When the tire is deflated, the radial spoke-like elements and the band stabilized thereby form a load-sustaining structure analogous to an elastic arch. In the design the band receives vertical, drag, and side loads from the road or ground surface and carries those loads in compression and bending; the radial spoke-like elements act as tension members to support the axle. A prime function, also, of the closely spaced radial elements is to stabilize the thin band against buckling. Although the patented design operates satisfactorily, improvements have been sought to improve the life and performance of a run flat tire as well as reducing manufacturing costs.